Learn Hardcore Indonesian: Sepupu laki-laki saya marah karena perangkat rapat hilang. - My male cousin is angry because the meeting device is missing.

Indonesian doesn’t use a linking verb like “to be” before adjectives/stative verbs. Marah itself serves as the predicate: Dia marah (He is angry). You can add aspect markers:

sedang/lagi marah (is currently angry)
sudah/telah marah (has gotten angry)

What’s the difference between marah karena and marah pada/kepada/sama?

marah karena explains the reason/cause: He’s angry because X.
marah pada/kepada marks the target of the anger: angry at someone. (kepada is more formal; pada is common.)
marah sama is informal for “angry at.” You can combine both: Dia marah kepada saya karena perangkat rapat hilang.

Is laki-laki the best way to say “male”? What about lelaki/pria/cowok?

All are possible, with different registers:

laki-laki: neutral, common.
lelaki: standard/literary.
pria: formal or polite (often in forms/signage).
cowok: informal/slang (male), counterpart cewek (female). Neutral female terms: perempuan (neutral), wanita (formal/polite).

Do I need the hyphen in laki-laki?

Yes, the standard spelling is laki-laki with a hyphen. You’ll also see lelaki (single word) as a variant. Writing laki laki without a hyphen is nonstandard.

Does perangkat rapat sound natural for “meeting equipment”? How is it different from peralatan/perlengkapan rapat?

perangkat rapat can mean “meeting device(s)/apparatus,” and is understood, especially in tech contexts (camera, speakerphone, mic).
peralatan rapat focuses on tools/equipment (more common for gear).
perlengkapan rapat is “meeting supplies/kit/setup.” For general office gear, peralatan rapat is often the safest choice.

How do I mark “the” in perangkat rapat hilang? Should I add itu or -nya?

Indonesian has no articles. To mark definiteness:

perangkat rapat itu hilang (that/the meeting equipment is missing)
perangkat rapatnya hilang (the meeting equipment is missing; or his/her meeting equipment, depending on context) Without a marker, definiteness is inferred from context.

Is perangkat rapat hilang a complete clause? Where’s the verb?

Yes. Hilang is a stative predicate meaning “is missing/has disappeared.” Indonesian often uses adjectives/stative verbs as predicates. Related forms:

menghilang: to disappear/vanish (intransitive)
menghilangkan: to cause something to disappear/remove (transitive)
kehilangan: to lose (subject suffers a loss) There’s no standard terhilang.

How do I say “He lost the meeting equipment” versus “The meeting equipment is missing”?

He lost it: Dia kehilangan perangkat rapatnya.
It is missing: Perangkat rapatnya hilang. The first blames the subject’s losing; the second describes the state of the equipment.

How do I express past or ongoing time here?

Add time words/aspect markers:

Past: tadi, kemarin, sudah/telah (e.g., Dia sudah marah karena…)
Ongoing: sedang/lagi (e.g., Dia sedang marah karena…)
Just now: baru saja Indonesian doesn’t change the verb form for tense.

Do I need a comma before karena?

Main clause + karena-clause: generally no comma. Example: Dia marah karena perangkat rapat hilang.
Karena-clause first: use a comma. Example: Karena perangkat rapat hilang, dia marah.

Can I start with the reason?

Yes: Karena perangkat rapatnya hilang, sepupu laki-laki saya marah.

Should I use yang: sepupu saya yang laki-laki vs sepupu laki-laki saya?

Both are correct. Sepupu laki-laki saya is a simple descriptive noun phrase. Sepupu saya yang laki-laki slightly emphasizes “the cousin of mine who is male,” often used to distinguish among multiple cousins.

Is perangkat singular or plural here? How do I make it plural?

Number is usually unmarked. Perangkat rapat can mean device(s)/equipment in general. To be explicit:

Plural: beberapa perangkat rapat, berbagai perangkat rapat, perangkat-perangkat rapat (the last is grammatical but less common than using quantifiers).
For mass equipment: peralatan rapat doesn’t need plural marking.

Is gara-gara okay instead of karena?

Yes, but it’s informal and can feel a bit more emotive/colloquial: Dia marah gara-gara perangkat rapat hilang. In formal contexts, prefer karena.

What other pronoun options could replace saya?

Formal/neutral: saya.
Informal/intimate: aku; possessive often as -ku (e.g., sepupu laki-lakiku).
Very informal/Jakarta: gue/gua (e.g., sepupu laki-laki gue). Choose based on formality and audience.

Do I need a classifier like sebuah before perangkat?

Only if you want to specify one item: sebuah perangkat (a device). For general equipment, no classifier is needed; for sets, you might say satu set peralatan rapat.

What’s the difference between hilang and tidak ada here?

hilang: lost/missing (implies it should be there but has gone).
tidak ada: not present/doesn’t exist there (neutral absence). Example: Perangkat rapat hilang (it’s gone); Perangkat rapat tidak ada di ruangan (there isn’t any in the room).